// Copyright 2006-2009 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef V8_LOG_UTILS_H_
#define V8_LOG_UTILS_H_

#include <stdio.h>

#include <cstdarg>

#include "src/allocation.h"
#include "src/base/compiler-specific.h"
#include "src/base/optional.h"
#include "src/base/platform/mutex.h"
#include "src/flags.h"
#include "src/ostreams.h"

namespace v8 {
namespace internal {

    class Logger;
    template <typename T>
    class Vector;

    enum class LogSeparator { kSeparator };

    // Functions and data for performing output of log messages.
    class Log {
    public:
        Log(Logger* log, const char* log_file_name);
        // Disables logging, but preserves acquired resources.
        void stop() { is_stopped_ = true; }

        static bool InitLogAtStart()
        {
            return FLAG_log || FLAG_log_api || FLAG_log_code || FLAG_log_handles || FLAG_log_suspect || FLAG_ll_prof || FLAG_perf_basic_prof || FLAG_perf_prof || FLAG_log_source_code || FLAG_gdbjit || FLAG_log_internal_timer_events || FLAG_prof_cpp || FLAG_trace_ic || FLAG_log_function_events;
        }

        // Frees all resources acquired in Initialize and Open... functions.
        // When a temporary file is used for the log, returns its stream descriptor,
        // leaving the file open.
        FILE* Close();

        // Returns whether logging is enabled.
        bool IsEnabled() { return !is_stopped_ && output_handle_ != nullptr; }

        // Size of buffer used for formatting log messages.
        static const int kMessageBufferSize = 2048;

        // This mode is only used in tests, as temporary files are automatically
        // deleted on close and thus can't be accessed afterwards.
        V8_EXPORT_PRIVATE static const char* const kLogToTemporaryFile;
        static const char* const kLogToConsole;

        // Utility class for formatting log messages. It escapes the given messages
        // and then appends them to the static buffer in Log.
        class MessageBuilder {
        public:
            // Create a message builder starting from position 0.
            // This acquires the mutex in the log as well.
            explicit MessageBuilder(Log* log);
            ~MessageBuilder() = default;

            void AppendString(String str,
                base::Optional<int> length_limit = base::nullopt);
            void AppendString(Vector<const char> str);
            void AppendString(const char* str);
            void AppendString(const char* str, size_t length);
            void PRINTF_FORMAT(2, 3) AppendFormatString(const char* format, ...);
            void AppendCharacter(char c);
            void AppendSymbolName(Symbol symbol);

            // Delegate insertion to the underlying {log_}.
            // All appended strings are escaped to maintain one-line log entries.
            template <typename T>
            MessageBuilder& operator<<(T value)
            {
                log_->os_ << value;
                return *this;
            }

            // Finish the current log line an flush the it to the log file.
            void WriteToLogFile();

        private:
            // Prints the format string into |log_->format_buffer_|. Returns the length
            // of the result, or kMessageBufferSize if it was truncated.
            int PRINTF_FORMAT(2, 0)
                FormatStringIntoBuffer(const char* format, va_list args);

            void AppendSymbolNameDetails(String str, bool show_impl_info);

            void PRINTF_FORMAT(2, 3) AppendRawFormatString(const char* format, ...);
            void AppendRawCharacter(const char character);

            Log* log_;
            base::MutexGuard lock_guard_;
        };

    private:
        static FILE* CreateOutputHandle(const char* file_name);

        // Implementation of writing to a log file.
        int WriteToFile(const char* msg, int length)
        {
            DCHECK_NOT_NULL(output_handle_);
            os_.write(msg, length);
            DCHECK(!os_.bad());
            return length;
        }

        // Whether logging is stopped (e.g. due to insufficient resources).
        bool is_stopped_;

        // When logging is active output_handle_ is used to store a pointer to log
        // destination.  mutex_ should be acquired before using output_handle_.
        FILE* output_handle_;
        OFStream os_;

        // mutex_ is a Mutex used for enforcing exclusive
        // access to the formatting buffer and the log file or log memory buffer.
        base::Mutex mutex_;

        // Buffer used for formatting log messages. This is a singleton buffer and
        // mutex_ should be acquired before using it.
        char* format_buffer_;

        Logger* logger_;

        friend class Logger;
    };

    template <>
    Log::MessageBuilder& Log::MessageBuilder::operator<<<LogSeparator>(
        LogSeparator separator);
    template <>
    Log::MessageBuilder& Log::MessageBuilder::operator<<<void*>(void* pointer);
    template <>
    Log::MessageBuilder& Log::MessageBuilder::operator<<<const char*>(
        const char* string);
    template <>
    Log::MessageBuilder& Log::MessageBuilder::operator<<<char>(char c);
    template <>
    Log::MessageBuilder& Log::MessageBuilder::operator<<<String>(String string);
    template <>
    Log::MessageBuilder& Log::MessageBuilder::operator<<<Symbol>(Symbol symbol);
    template <>
    Log::MessageBuilder& Log::MessageBuilder::operator<<<Name>(Name name);

} // namespace internal
} // namespace v8

#endif // V8_LOG_UTILS_H_
